The Sava Hills are the eastern part of the Slovene Prealps. They are oriented in the east-west direction and are located to the north and south of the Sava River in central and eastern Slovenia, among the Ljubljana Basin to the west, the Celje Basin to the north, the Lower Carniola valley system and the Krško Basin to the south, and the Sotla Hills to the east. They cover an area of 1,909 square kilometres (737 sq mi) and are the largest Slovenian mesoregion.